I run a back up utility called SyncBackSE. It will copy PST files in use and allow me to aggregate several folders on my PC into one folder. This resolves the issue of backing up files in use and multiple folders. (Back up several folders from Master drive to one folder on local back up drive. Use Syncdocs to sync that single folder to GDocs.

I am interested in syncing PST files for backup, too.
How is this working for you?
I envision creating a backup folder, placing the PST in there, and opening the PST from Outlook. I understand that it will only sync when Outlook is shut down.
Any issues with starting/stopping outlook when the sync is running? Sure don't want to corrupt the file, outlook is fussy enough all on its own.
Thanks for feedback and suggestions.